How do I completely erase my hard drive and restart my computer to factory settings?

I have a windows vista and want to give it away but also want to take the hard drive as spare memory. It is full and I do not know how to completely erase all data from it. does anyone know how to do this and then how to restart it again

Most Helpful Girl

Do what I do, turn off the computer and then turn it back on and while its loading press CTRL +F11 at the same time..there will be a screen and itll ask you a ques...I forget now, did it so many times I should know by now..but just press ctrl+F11 and it should help you get it back to factory settings.